The invention is concerned with a system for automatic adjustment to external mirrors when driving in curves in accord with claim 1 and the invention is additionally concerned with an external mirror with a system of the above type in accord with claim 15.
In the case of driving through curves with vehicles, especially in the case of commercial vehicles with a tow, tractor-trailers, articulated buses and the like, in the inside of the curve the line of sight is limited due to the bending of the vehicle combination. This often leads to deadly accidents involving pedestrians and bicycle riders, who are found on the inside of the curve and are not seen by the driver because of the said limitations of sight as the vehicle turns. In order to avoid this problem, systems are already in common knowledge, in which the mirror on the inside of the curve adjusts itself automatically to correspond to the turning motion. This is done so that the visible area is held over the entire length of the vehicle, all the way to the end.
From WO-A-95 23079, such a system has been made known, in which, where tractor-trailers are concerned in the curve driving, the changing differential in distance between the tractor and the trailer is determined by means of ultrasonic sensors. From this changing differential of distance, as progress is made around the curve, that is, the bending of the tractor in relation to the trailer, a signal to cause the mirror to track the inside curve is achieved. Another similar system based on ultrasonics is made known by the U.S. Pat. No. 5,306,953 and the U.S. Pat. No. 5,132,851.
From the said WO-A-95 23079, the practice is known of installing a magnetic field sensor on the tractor as well as on the trailer, however, like a magnetic compass, both sensors do react to the magnetic field of the earth.
From the difference in signals from the two magnetic field sensors, a signal for the turning of the vehicle around its vertical axis is arrived at. The use of magnetic sensors leads, in any case, to problems, since because of the multitude of electrical operators in a vehicle, some having substantial current demandsxe2x80x94because of the low voltagexe2x80x94large magnetic fields arise, which disturb the functioning of the magnetic field sensors.
Setting out from the WO-A-95 23079, it is therefore a purpose of the present invention, to make available a system for the automatic adjustment of external mirrors of vehicles, during driving in curves, especially in the case of commercial vehicles with a tow and tractor-trailers, which system operates reliably and is adaptable even for the most different vehicles. Besides this, it is another purpose of the present invention to present a combination of a system of this type combined with a conventional external mirror for commercial vehicles. The achievement of these purposes is brought about by the features of the claims 1 and 15.
Because of the fact, that the turning motion of the vehicle about its vertical axis can be determined by a turn-rate sensor operating on the principle of a gyroscope, the functioning of the tracking system cannot be impaired by, for instance, contaminations, such as invariably enter in the case of commercial vehicles nor by magnetic fields due to the electrical usage in the vehicle. Thereby, it becomes possible, to install the turn-rate sensor at an optional point in the vehicle and especially is it possible, to integrate the turn-rate sensor into a conventional external mirror, so that the automated, tracking external mirror is made as a total system and can be sold as such.
In accord with an advantageous embodiment of the invention, the mirror adjustment apparatus of the tracking system is the electro-magnetic mirror adjustment system of a conventional external rear view mirror, so that any additional components are avoided.
In accord with an advantageous development of the invention, the adjustment of the external mirror is made continually in accord with the sensor measured turning of the vehicle about the vertical axis. In this way backward mirror movements, which could irritate the driver are avoided.
In accord with a further advantageous embodiment of the invention, the travel speed of the vehicle is taken into consideration as an input to the tracking of the mirror. That is, at a greater driving speed, the adjustment is effected more rapidly than at lower driving speeds. Thereby, the method of functioning of the system in accord with the present invention in various speed ranges is assured. An adjustment which is too slow or too rapid, that is, the tracking movement of the external mirror is thereby avoided.
In accord with another advantageous embodiment of the invention, the tracking movement during curve driving is done only in a definite speed range between a minimal speed and a maximum speed. Thereby, the mirror does not move at all during truck park maneuvering, which is done with very low speeds, thus avoiding irritation on the part of the driver.
In accord with an advantageous development, the speed of the vehicle is determined by direct branching from an existing speed signal which is normally found in vehicles, which signal is diverted to the control device. An additional speed sensor is superfluous.
In accord with a further, advantageous embodiment, the speed of the vehicle, with which the external mirror is adjusted, corresponds to, i.e. is proportional to the turning speed of the vehicle about its vertical axis. On this account, the evaluation of a driving speed becomes superfluous.
In accord with a further advantageous embodiment of the invention, the tracking of the external mirror corresponds to the determined rate of turning between a zero-point and a maximum allowable angle in two opposite turning directions. Then the sensor detects a turning about a vertical axis upon the beginning of a curve, then the deflection of the external mirror is to the outside, and if the sensor detects, that the vehicle again resumes a directly forward movement, then the external mirror is reset in the opposite direction to the zero-point.
Alternatively, it is also possible, with a simple embodiment of the invention, to bring about a situation in which the adjustment of the external mirrors during curve driving, as determined by the detected degree of turn, is effected in only one direction and the subsequent resetting into a zero position occurs automatically after a certain length of time. This length of time, or said duration, when this system is used, can be definitely fixed, or it can align itself in accord with the vehicle speed or the rate of turn within the curved driving.
In accord with a further advantageous embodiment of the present invention, the system for tracking is subject to manual disconnection. This is of advantage in the course of maneuvering or if the driver feels himself irritated by the automatic tracking.
In accord with a further especially advantageous embodiment of the invention, the turn rate sensor for tractor trailers is installed in the cab. In this case, in the trailer itself no components of the invented tracking system have been provided. This would make sure, that optional trailers can be employed, since the system is exclusively situated in the cab. In the matter of mirror adjustment, it is of especial value when the tracking system is integrated in a conventional external mirror installation with electromotive control possibilities. In this case, the external mirror, complete with automatic tracking can be offered as a complete system. The remaining subordinate claims concern themselves with further advantageous embodiments of the invention.